Redd explains that the absorption and breakdown of fat-soluble vitamins depends, in part, on healthy bile secretion from one's gallbladder. "If our patients have had their gallbladders removed, we ...

That fat-soluble substance became known as vitamin A. Clockwise from right: Casimir Funk identified the first vitamin, later called B. Carl Peter Henrik Dam found K, and Elmer McCollum discovered A.